HIGH-GRADE MALIGNANT NON-HODGKINS-LYMPHOMAS DIFFER FROM LOW-GRADE LYMPHOMAS IN THE EXTENT OF APOPTOSIS AND THEIR EXPRESSION OF BCL-2, MCL-1, BAX AND P53

In this study, we investigated the extent of apoptosis in 82 non-Hodgk in's lymphoma and 4 reactive follicular hyperplasias and correlated th e findings with the extent of apoptosis as determined by the 3'-end la belling method of the apoptotic DNA, To study the influence of apoptos is-regulating proteins bcl-2, bar, mcl-1 and p53 on the extent of apop tosis, we also immunostained the samples with. antibodies to them. The results show that there is a significant difference in the extent of apoptosis between low-and high-grade non-Hodgkin's lymphomas, the latt er on average showing considerably more apoptotic cells (0.38 +/- 0.30 and 1.44 +/- 1.35%, respectively; p = 0.001). In line with this diffe rence, high-grade lymphomas had significantly more cases with a weak e xpression of bcl-2 and strong expression of bar (p = 0.00008 and p = 0 .016, respectively). They also show-ed significantly more cases with a positive p53 immunoreactivity (p < 0.00001) and strong mcl-1 immunore activity (p = 0.018). The results suggest that apoptosis-affecting gen es bcl-2. bar, mcl-1 and p53 all take part in the regulation of apopto sis in malignant non-Hodgkin's lymphomas and contribute to a different level of apoptosis between high-and low-grade non-Hodgkin's lymphomas .